[ 175 j 1^8 



Take six ounces of common salt, mix it well with three ounces ot 

 powder of black oxyde of manganese; put this mixture in a strong 

 bottle, with two ounces of water, cork it well with a common cork. 



Keep this bottle in any part of the laboratory farthest from the 

 stove or fire-places. In a phial put a pound and a half of sulphuric 

 acid, (oil of vitriol,) and keep this phial near the other bottle, with a 

 small cordial glass and an iron spoon j and this is the manner of using 

 it: Put into the small glass, two-thirds of a spoonful of oil of vitriol, 

 pour it into the large bottle, and there will issue a white vapor. 



The bottle should be moved about through the laboratory, holding 

 it high up that the vapor may be well spread in the air. 



When the vapor ceases, the bottle may be corked, and replaced: 

 even should there be no perceptible difference between the interior 

 and exterior air, during the fifth age of the worms, it is good to re- 

 peat this fumigation three or four times a day in the manner just ex- 

 plained. When repeating the fumigation, the quantity of oil of vitriol 

 poured into the large bottle may be diminished. The stated quantity 

 of ingredients will be sufiicient for a laboratory of five ounces of eggs. 

 The bottle may be left open an hour or two in the last days of the 

 fifth age of the silkworms; and placed here and there in the labora- 

 tory, and even on the corners of the wicker hurdles, to diffuse the 

 vapor thoroughly. 



This remedy may be employed, whenever, on going into the labora- 

 tory, the air appears to have an unpleasant effluvia, and that there is 

 any closeness, or difficulty of breathing. 



1st. It may take place when the litter of the silkworm is removed, 

 particularly in the fifth age. 



2d. When in moist weather the air of the laboratory continues 

 damp, even after having made the blaze, which renders the fermenta- 

 tion still quicker. 



This fumigation may be of use also towards the end of the fourth 

 age, if the air be perceived to be impure. It may not be needed in 

 all cases, until after the fourth age of the silkworms, and at the be- 

 ginning of the fifth age. 



If there are several small fire-places in the laboratory, and that blazes 

 are frequently made in them to agitate the air, fumigations will not 

 be so much required. 



It must be observed that care should be taken not to drop any of the 

 oil of vitriol, either on the skin or clothes, as it burns; and to hold 

 the bottle above the height of the eyes and nose, when it is open, be- 

 cause the vapor is very searching, and would be dangerous and un- 

 pleasant. Should the substances in the bottle harden, a little water 

 may be added, and stirred with a small stick. This easy remedy is 

 more powerful than all perfumes commonly used, and produces five 

 advantages in the laboratory. 



1st. The vapor in spreading immediately, destroys any unpleasant 

 offluvia. 



2d. It diminishes the fermentation of the litter, and dries it up. 



3d. It neutralizes the effect of all the miasmata, and deleterious 

 :^manations that might attack the health of the silkworms. 



